Electroplating processes employing horizontally rotating barrels are known within the art as disclosed, for example, in U.S. Pat. Nos. 3,860,320 (Danner) and 2,249,609 (Jackson). In such a system, a cable extends into the barrel through one or both ends at the axis of rotation of the barrel. Each cable typically has a cathode member secured to the free-end within the barrel for conducting plating current through an electrolyte to the workpieces tumbling in the barrel. It is common practice to secure the cathode member to the end of the cable by soldering, crimping,swaging or the like as disclosed, for example, in U.S. Pat. No. 3,844,923 (Sandrock). This provides for intimate contact between the conductor and the cathode member.
A problem in the field has been the buildup of plate material on the steel knob forming the cathode member of the dangler cable. This buildup has reached the degree where damage to the finished workpieces has been a problem. Such buildup of plate can become severe so as to damage the work during the tumbling process. One example where this problem occurred resulting in damage to the work was in the cooper cyanide plating of zinc blanks which are sold to the U.S. Mint and struck in the manufacturing of U.S. one cent pieces.
A second problem is that of the wasted material represented by the excess copper "buildup" on the dangler knob or cathode member. It has been desired when the danglers become unusable that the knob or cathode member be severed from the cable and the excess material by reused as anode material in the plating process. However, this object has not been achieved due to the large portion of steel represented by the knob which acts as a substrate to this buildup of copper. The iron in the steel causes a contamination of the plating solution. In addition, should the knob be soldered to the cable, the tin and lead represent additional contaminants. As a result, the "used" knobs have been sold at a discount to copper scrap dealers.
Several manufacturers have in the past manufactured prototype danglers having replaceable copper knobs. The purpose of this design was to permit the knob or cathode member after severe buildup of copper had occurred to be removed and then used as anode material resulting in the complete deterioration of the copper buildup and the copper knob itself in the electroplating process.
The problems encountered with the replaceable copper knob design were twofold: First, the actual replacement of the copper knob was somewhat unwieldy resulting in excess machine downtime. Second, the cost of a dangler with replaceable copper knob(s) has been prohibitive. The dangler cable itself can withstand the abrasion which occurs during two "dangler knob lives". As a result, this additional cost does not offset the disadvantage of not using the "knob" as anode material.